Phototherapy Basics Information

1. 620-630nm is the first treatment window of light on the skin

2. 605nm, 610nm and 620nm is the peak absorption of haemoglobin, so the penetration depth of 620nm --- 630nm light on the skin is basically proportional to the wavelength.

3. short wavelengths less than 480 have a tanning effect.

4. 540 and 580 is a vascular disease The light absorption spectrum of melanin is monotonically decreasing with increasing wavelength. Again, in order to avoid the side effects of <480nm and to take into account that melanin is only distributed within the epidermis, shallow penetration is required. Therefore, the lower limit of 540nm can be used to treat vascular lesions and at the same time remove the darkness very effectively. If there are no vascular lesions on the face, then choose the lower limit of 590nm, which can not only remove wrinkles and skin rejuvenation, but also remove melanin, achieving the effect of "skin rejuvenation and whitening".

6. Wrinkle skin rejuvenation is the target of photons is dermal tissue. On the one hand, it requires a certain depth of penetration. The longer the wavelength in the visible to near infrared range, the deeper the penetration. On the other hand, dermal tissue is much larger than haemoglobin, microvessels and melanin, and of course requires much more heat. The longer the wavelength, the more efficient the photothermal conversion. Therefore the lower limit of the wavelength for wrinkle rejuvenation is chosen near the lower limit of the first treatment window. When photorejuvenation is used to improve the structure of the dermis, a wavelength between 596-610nm is chosen, which overlaps with the wavelength used for hair removal. Rejuvenation of hair-free areas is not a problem, but rejuvenation of hairy areas may result in hair removal at the same time. This should also be taken into account when performing other treatments.

7. The root of the hair is 3-5mm below the epidermis, so hair removal requires a wavelength that penetrates deeper into the soft tissue. Also long wavelengths with high photothermal conversion efficiency are required due to the large size of the hair follicles to be destroyed, which are 20-100um in diameter. On the other hand, if the wavelength is too short, the melanin in the epidermis will be absorbed first and heat will be generated in the epidermis before it penetrates deep into the hair follicle, which will easily cause epidermal damage. The lower limit of wavelength for hair removal is generally chosen at the lower limit of 620nm for red light, with a range of variation between 620-625nm.

8. All photorejuvenators in China today have a fixed wavelength at the top end and a different filter at the bottom end depending on the needs. In other words, a photorejuvenator is a continuous spectrum light source with a limited and variable spectral range. For example, for acne treatment, the wavelength range is 380-1200nm; for vascular or pigmented lesions, the wavelength range is 520-1200nm; for skin rejuvenation and whitening, 460-470nm; for hair removal, the filters are limited to 460-470mm.

9. exists in an abundance of wavelengths. When the human body is exposed to photons, different tissue components within the skin selectively absorb different wavelengths, so there are different effects occurring in a single exposure. For example, when treating with 430-1200nm, in addition to doing acne to implement sterilization and clearing, redness is also removed. This is when the haemoglobin Z high absorption peak of 415nm comes into play, which is not found in the 520-1200nm filter. Also, the wavelengths required for tanning, wrinkle removal and hair removal are all included. This is why photonics has a spectrum of therapeutic effects.

10. With multiple wavelengths acting simultaneously, multiple effects can be achieved with good control. If not well mastered, there is a risk that the desired effect may coexist with side effects. For example: too much germicidal UVC may blacken the skin; when removing wrinkles, burn off beard hair that should not be removed; for darker skin tones to remove redness, it is better to use 460-470nm than 520-1200nm, as the wavelength increases and melanin absorption decreases.